Electro-magnetic relay



Sept. 1, 1959 E. B. ANGOLD ELECTRO-MAGNETIC RLEAY Filed Feb. 5, 1957 v11111 1| n 2 8 T R l/ T 4 2 a n M United States Patent f) 'ELECTROMAGNETIC RELAY Edward Barnabas Angold, Ramsden Heath, England, assignorto The Plessey Company-Limited, Ilford, England, a British companyApplication February '5, 1957, Serial No. 638,420

Claims priority, application Great Britain February 13, 1956 7 Claims.(Cl. 200-104) This invention relates to electromagnetic relays and hasfor an object to provide an improved relay of the kind, hereinaftercalled the kind'specified, in which a substantially. fiat armature,extending longitudinally of the relay winding, is arranged between therelay winding and the contacts to be operated.

in a previously known electromagnetic relay inwhich a substantially flatarmature extends longitudinally of the relayvwinding and isarrangedbetw'een the relay winding and the contacts to be operated, thearmature co-operates with all end of the core which is turned up andback over the coil to constitute a pole piece, while the armature ispivoted by edge contact on a yoke which extends forwardly over the coilfrom the rearward end of the core towards the pole piece. The magneticflux thus passes from the yoke to the armature through the edgecontactconnection, and back to the pole piece and the armature projectingoverthe latter, vwhile no appreciable flux passes through the part ofthe armature beyond the line of edge contact.

According to the present invent-ion two pole pieces of a relay of'thekind specified extend inwardly from the two ends of the core of therelay winding, and the armature is 'pivotally movable about a transverseaxis at or near its centre, one end of the armature extending at theinnerside of one of the pole pieces, and its other end extending at theouter side of the other pole piece. As a result the polar momentsexerted upon the armature by the magnetic attraction of the two polesact additively, and each passage of the flux between the stationary core:structure and the armature is utilised to contribute to the availablecontact-actuation force, so that the relay will develop a greatactuation force in relation to its size.

In one particular form of the relay according to the invention thearmature is provided with projecting pin elements; A bridge member orstructure, supported on the'inner'pole piece and extending across thepole piece at the outerside of the armature serves to support a'stack ofcontact-springs extending along the outerside of the core-and-armatureassembly. The stack of contact springs and the bridgepiece are securedby screw means extending through suitable apertures inthe armature, inthe bridge member and in or between insulating'spacers separatingthecontact blades, and each' side ofthe bridge member or structure has aprojection extending to, and supported, preferably under slight elasticdeformation load, against the inner surface of the other pole piece.These projections areformed with recesses attheir outer side, in whichthe two pin elements'of the armature are respectively supported'forpivotal movement. The pin elements may be of square or rectangularcross-section and rest in similarly shaped recesses to obtain lowfriction loss' and low cost ofmanufacture.

According to a modification the projecting pin elements of the armatureof the bridge and the recesses in the projections may be omitted. A thinflexible sheet of non- Patented Sept. 1, 1959 ferromagnetic material issecured to the outer surface of the inner pole piece and to the innersurface of that part of the armature which faces the other pole piece.Pivotal movement of the armature is possible by flexing of this sheetround the edge of the inner pole piece. In order to reduce stress in thesheet, this edge is preferably rounded with a suitable radius. Theflexible sheet, in addition to hingedly connecting the-armature to theinner pole piece, also locates it by preventing any movement in theplane of the armature.

The armature actuates the movable'contact springs by one or moreactuating pins or cards co-operating with the outer surface of thearmature at the outer side of the other pole piece, which extend throughapertures in the said other pole piece and aligned apertures of at leasttwo contact spring blades or dummy blades, while 'being supported by ashoulder or the like on the surface of the spring to be actuated.

Excessive inward movement of the stationary and/ or movable contactsprings is preferably prevented by one or more spacer pins or cardsguided similarly to the actuating pins or cards by aligned apertures intwo springs or similar blades, said spacer pins having shoulderssupported on opposed surfaces'of at least one movable contact spring anda relatively rigid blade extending between said contact spring and thecore and armature assembly. This relatively rigid blade may serve as astationary contact blade.

Two embodiments of the invention will now be described in more detailswith reference to the accompanying drawings, in which:

Figures 1 and 2 are respectively a top plan view and a side elevation,partly in section, of one embodiment, and

Figure 3 is a side elevation of the armature and core assembly of theother embodiment.

Referring now first to Figures 1 and 2, the relay has a winding 5surrounding a core 6 of magnetisable material one end of which is bentat right angles to form a shank 7, and the end of which is once morebent at right angles to form a pole piece 8 extending, at the outer sideof the winding 5, substantially parallel to the core 6. A contact stack,generally referred to by reference numeral 9, is secured to the polepiece 8 by a screw 10, with the interposition of a bridge member 2,which is formed of nonmagnetic sheet metal blanked to appropriate shapeand bent to an inverted U profile. The flanges 2a of the U-profilebridge member rest on the pole piece 8, while the web 2b, preferablyreinforced by a transverse pressed ridge 2c, is spaced from the polepiece 8 by the flanges 2a. A second pole piece 13, constituted by a fiatpiece of magnetisable material bent to approximate L shape, is securedwith one of its limbs to the free end of the core 6, for example byriveting, while its other limb extends along the outer side of thewinding 5, in a direction opposite to that of the pole piece 8, but at aslightly greater distance from the winding 5, for areason which willsoon become apparent. The flanges 2a of the bridge member 2 are extendedbeyond the inner end of the Web portion 21b to form support brackets 20which engage the inner surface of the second pole piece 13, theconstruction being such that when the screw 10 is tightened, the ends ofthe support brackets 2c are-pressed against the inner surface of thepole piece 13 between the respective ends of the web portion 2b and thepole piece 13. The support brackets 20 are each formed with anapproximately rectangular cut-out 2d, and these cut-outs accommodatefulcrum pins 1b which project at opposite sides from a flatferro-magnetic armature 1, which is thus pivotally supported on thebridge member -2-in such manner that one half of-the armature faces theouter surface of the pole piece 8, While the other half of the armaturefaces the inner surface of the other pole piece 13. The contact stack 9comprises a flexible contact blade 14 carrying a contact block 15constituting the movable contact of the relay, and two fixed contactblades 16 and 17, respectively carrying the contact blocks 18 and 19,constituting the stationary contacts. The inner fixed contact blade 16is relatively rigid, while the outer fixed contact blade 17 is flexiblesimilarly to the movable contact blade 14. A resilient auxiliary ordummy blade 20 is also provided in the stack. A spacer 4, having anabutment portion 4a against which the opposed surfaces of the fixedblades 16 and 17 are supported, serves to maintain the fixed contacts 18and 19 at the requisite relative distance so that contact block 19 isclear of contact block 15 when the relay is in the illustrated,tie-energised position, in which contact block 15 rests against contactblock 18 carried by the relatively rigid fixed blade 16.

When the relay windings are energised, magnetic flux will flow acrossthe air gaps visible in the drawing, between the pole piece 8 and thelower side (in Figure 2) of the right-hand half of the armature and alsobetween the pole piece 13 and the upper side of the left-hand side ofthe armature. The resulting attraction forces at both air gaps actadditively, exerting a clockwise torque upon the armature about itsfulcrum axis. This torque is utilised for moving, by means of anactuating card 3, the flexible blade 14 from the illustrated inoperativeposition, in which the contact block 15 is in contact with block 18, tothe operative position, in which this contact is broken and contactblock 15 instead makes contact with contact block 19 on blade 17. Theactuating card 3 extends through aligned slots in the blades 14 and 2t),and has a shoulder 3a which acts upon the underside of the blade 14,While its lower end 3b co-operates with the upper surface of theleft-hand half of armature 1. A second shoulder 30 of the actuating card3 is supported against the lower side of the auxiliary blade 20, whichblade provides a return force tending to restore the armature 1 to itsillustrated inoperative position. Between the various contact springsclamped by means of the screw 10, insulating discs 21 are interposed. Inthe illustrated embodiment two sets of contact blades are provided, eachwith an actuating card 3 and spacer 4, one set at each side of theclamping screw 1%, but it will be readily understood that either asingle set or more than two sets may alternatively be employed withoutexceeding the scope of the present invention.

Figure 3 illustrates a modified armature-and-core assembly; this may beequipped with a contact stack, spacers, and actuating pins which areidentical with those shown in Figures 1 and 2, and which have beenomitted in the drawing to simplify the figure. In this embodiment thepivotal connection between the armature 1 and the pole piece 8 which isintegral with the core 6, is effected by means of a flexible sheet 11 ofnon-magnetic material which at one end is connected to the armature, forexample by rivets 22, while the other end of the flexible sheet 11 issecured to the pole piece 8, for example by being clamped between thelatter and the bridge member 12. In order to define more closely theZone of flexure, a second line of attachment of the sheet to thearmature is preferably provided by rivets or screws 23 fixed in thearmature 1, preferably with the interposition of a clamping bar 24 atthe back of the sheet 11. The bridge member 12 itself may be constructedsimilarly as illustrated in Figure 2, except that the recesses 2dprovided in the bracket portions 20 of bridge member 2 are omitted inthe bracket portions 120 of the bridge member 12.

What is claimed is:

1. An electromagnetic relay, comprising in combination, a core, firstand second pole pieces associated with the core, a free end portion toeach pole piece, the free end portions being turned inwardly to overliethe core and to face towards each other, on the same side of the core,

in separated relationship, a cradle-like bridging member blanked outfrom a single piece of non-magnetic material bridging the pole pieces,readily releasable means for securing the bridging member to one of thepole pieces so that the bridging member is held in contact with theother one of the pole pieces in such manner as to ensure accuraterelative positioning of the pole pieces and an armature pivotallysupported by the bridging member for balanced pivotal movement about atransverse axis, so that one end thereof is located between a pole pieceand the core, and so that the other end co-operates with the remainingpole piece on the side thereof remote from the core.

2. An electromagnetic relay, comprising in combination, a core, awinding on the core, first and second pole pieces magnetically connectedwith the core, an end portion of each pole piece being turned inwardlyto overlie at least a part of the winding so that the end portions facetowards each other on the same side of the core with a gap between theend portions, a blanked out channelled member bridging the gap, readilyreleasable means for securing the bridging member to one of the polepieces so that the bridging member is held against the other pole piecein such manner as to ensure accurate relative positioning between thepole pieces, a set of contact springs supported by said bridging memberand secured thereto by the means securing the bridging member to saidone pole piece and an armature pivotally mounted on the bridging memberto be swingable between the gap with one limb of the armature locatedbetween a pole piece and the winding and with the other end of thearmature co-operating with that side of the remaining pole pieces whichis remote from the winding.

3. An electromagnetic relay, comprising in combination, a core, firstand second pole pieces associated with the core, a free end portion toeach pole piece, the free end portions being turned inwardly to overliethe core and to face towards each other on the same side of the core, inseparated relationship, a member bridging the separation between thepole pieces, screw means for securing the bridging member to one of thepole pieces, a projection extending from each side of the bridgingmember, each projection extending to, and being supported against thatsurface of the other pole piece which is adjacent the winding so thatwhen the bridging member is secured to the one pole piece slight elasticdeformation is produced between the pole pieces, and an armaturepivotally mounted on the bridging member to be swingable between the gapwith one limb of the armature located between a pole piece and thewinding and with the other end of the armature co-operating with thatside of the remaining pole piece which is remote from the winding.

4. An electromagnetic relay, comprising in combination, a core, awinding on the core, first and second pole pieces magnetically connectedwith the core, an end portion of each pole piece being turned inwardlyto overlie at least a part of the winding so that the end portions facetowards each other on the same side of the core with a gap between theportions, a member in the form of blanked fiat material bent to a Uprofile bridging the gap, means for securing the bridging member to oneof the pole pieces so that the bridging member bears upon the other polepiece in such manner as to produce elastic deformation between the polepieces, and an armature pivotally mounted on the bridging member to beswingable between the gap with one limb of the armature located betweena pole piece and the winding and with the other end of the armatureco-operating with that side of the remaining pole piece which is remotefrom the winding.

5. An electromagnetic relay, comprising in combination, a core, awinding on the core, first and second pole pieces magnetically connectedwith the core, an end portion of each pole piece being turned inwardlyto overlie at least a part of the winding so that the end portions facetowards each other on the same side of the core with a gap between theend portions, a member, in the form of blanked flat material bent to a Uprofile and having a pressed stiifening ridge extending across the webof the U bridging the gap, means for securing the bridging member to oneof the pole pieces so that the bridging member bears upon the other polepiece in such manner as to produce elastic deformation between the polepieces and an armature pivotally mounted on the bridging member to beswingable between the gap with one limb of the armature located betweena pole piece and the winding, and with the other end of the armaturecooperating with that side of the remaining pole piece which is remotefrom the windmg.

6. An electromagnetic relay, comprising in combination, a core, awinding on the core, first and second pole pieces magnetically connectedwith the core, an end portion of each pole piece being turned inwardlyto overlie at least a part of the winding so that the end portions facetowards each other on the same side of the core with a gap between theend portions, a channelled blankedout member bridging the gap, readilyreleasable means for securing the bridging member to one of the polepieces so that the bridging member is held in contact with other polepiece in such manner as to ensure accurate relative positioning of thepole pieces, a set of contact springs supported by said bridging memberand secured thereto by the means securing the bridging member to saidone pole piece, an armature pivotally mounted on the bridging member tobe swingable between the gap with one limb of the armature locatedbetween a pole piece and the winding and with the other end of thearmature co-operating with that side of the remaining pole pieces whichis remote from the winding, at least one through aperture formed in theother pole piece, and an actuating card in said contact spring set, thecard being engageable by the armature.

7. An electromagnetic relay, comprising in combination, a core, awinding on the core, first and second pole pieces magnetically connectedwith the core, and an end portion of each pole piece being turnedinwardly to overlie at least a part of the winding so that the endportions face towards each other on the same side of the core with a gapbetween the portions, a member in the form of blanked flat material bentto a U profile bridging the gap, readily releasable means for securingthe bridging member to one of the pole pieces so that the bridgingmember bears upon the other pole piece in such manner as to produceelastic deformation between the pole pieces, an armature pivotallymounted on the bridging member to be swingable between the gap with onelimb of the armature located between a pole piece and the winding andwith the other end of the armature co-operating with that side of theremaining pole piece which is remote from the winding, and a set ofcontact springs supported by said bridging member and secured thereto bythe means securing the bridging member to said one pole piece.

References Cited in the file of this patent UNITED STATES PATENTS2,422,986 Ring June 24, 1947 2,455,049 Edwards et a1 Nov. 30, 19482,510,157 Towner et al. June 6, 1950 2,664,478 Johansson Dec. 29, 19532,760,026 Horlacher Aug. 21, 1956

